feat(tickets): add ticket collections and edit history

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/collections/tickets/TicketVotes.ts

@@ -0,0 +1,37 @@
+import type { CollectionConfig } from "payload";
+
+export const TicketVotes: CollectionConfig = {
+  slug: "ticket-votes",
+  admin: {
+    group: "Helpdesk",
+    defaultColumns: ["ticket", "user", "createdAt"],
+  },
+  access: {
+    read: ({ req }) => Boolean(req.user),
+    create: () => false,
+    update: () => false,
+    delete: () => false,
+  },
+  indexes: [
+    {
+      fields: ["ticket", "user"],
+      unique: true,
+    },
+  ],
+  fields: [
+    {
+      name: "ticket",
+      type: "relationship",
+      relationTo: "tickets",
+      required: true,
+      index: true,
+    },
+    {
+      name: "user",
+      type: "relationship",
+      relationTo: "users",
+      required: true,
+      index: true,
+    },
+  ],
+};

src/collections/tickets/Tickets.ts

@@ -1,5 +1,5 @@
 import { CollectionConfig } from "payload";
-import { requirePermission, hasPermission } from "@/utils/access-control/hasPermission";
+import { hasPermission } from "@/utils/access-control/hasPermission";
 import {
   CLOSING_STATUSES,
   STATUS_LABEL,
@@ -30,6 +30,20 @@ const systemEntry = (message: string, createdAt?: string) => ({
   created_at: createdAt ?? new Date().toISOString(),
 });
 
+function isRecord(value: unknown): value is Record<string, unknown> {
+  return typeof value === "object" && value !== null && !Array.isArray(value);
+}
+
+function immutableEditValue(value: unknown): string | null {
+  if (!isRecord(value)) return null;
+  return JSON.stringify({
+    before: value.before,
+    after: value.after,
+    editedBy: resolveUserId(value.editedBy),
+    editedAt: value.editedAt,
+  });
+}
+
 export const Tickets: CollectionConfig = {
   slug: "tickets",
   admin: {
@@ -74,6 +88,17 @@ export const Tickets: CollectionConfig = {
         // entry appended by the create server action instead.
         if (!prev || !prev.id) return data;
 
+        if (next.editHistory !== undefined) {
+          const previousEdits = Array.isArray(prev.editHistory) ? prev.editHistory : [];
+          const nextEdits = Array.isArray(next.editHistory) ? next.editHistory : [];
+          const existingEditsChanged = previousEdits.some(
+            (entry, index) => immutableEditValue(entry) !== immutableEditValue(nextEdits[index]),
+          );
+          if (nextEdits.length < previousEdits.length || existingEditsChanged) {
+            throw new Error("Ticket edit history is immutable.");
+          }
+        }
+
         const entries = [...((next.activity as unknown[]) ?? [])];
         const now = new Date().toISOString();
         const changes: string[] = [];
@@ -230,6 +255,41 @@ export const Tickets: CollectionConfig = {
         },
       ],
     },
+    {
+      name: "editHistory",
+      type: "array",
+      admin: {
+        readOnly: true,
+        description: "Immutable before/after snapshots captured when the author edits a ticket.",
+      },
+      fields: [
+        {
+          name: "before",
+          type: "json",
+          required: true,
+        },
+        {
+          name: "after",
+          type: "json",
+          required: true,
+        },
+        {
+          name: "editedBy",
+          type: "relationship",
+          relationTo: "users",
+          required: true,
+        },
+        {
+          name: "editedAt",
+          type: "date",
+          required: true,
+          admin: {
+            readOnly: true,
+            date: { pickerAppearance: "dayAndTime" },
+          },
+        },
+      ],
+    },
     {
       name: "closedAt",
       type: "date",